1. Field of the Invention
This invention relates to a glassy metal composite material, more particularly to a glassy metal composite material including a plurality of porous metal particles dispersed in an amorphous metal matrix.
2. Description of the Related Art
Compared to Pd-based and Zr-based glassy metals, Mg-based glassy metals have an advantage of a relatively low density, but have undesired intrinsic brittleness at room temperature. In addition, when an external compression stress is applied on the Mg-based glassy metal, the Mg-based glassy metal is likely to fracture prior to a yield point thereof due to its intrinsic brittleness.
There are two known methods for improving ductility of the Mg-based glassy metal by addition of secondary phase particles into a matrix of the Mg-based glassy metal. One is conducted through addition of particles with a hardness less than that of the matrix, which is the so-called crack bridging model. The other is conducted through addition of particles with a hardness higher than that of the matrix, which is the so-called crack deflection model.
D. G. Pan et. al. (Applied Physics letters, 89, 261904, 2006) disclose addition of 8 vol % Nb particles having a particle diameter ranging from 20 μm to 50 μm into a Mg65Cu20Ag5Gd10 matrix so as to improve the ductility thereof. The result of stress/strain relation (not shown) shows that an engineering strain of up to 18% can be achieved, but an elastic strain at an initial stress-provided state is merely up to 2%.
Ying-Kun Xu et. al. (Acta Material 53, 2005, 1857-1866) disclose addition of 10%-30% vol TiB2 particles having a particle diameter of 10 μm into a Mg65Cu7.5Ni7.5Zn5Ag5Y10 matrix so as to improve the ductility thereof. The result of stress/strain relation (not shown) shows that compression strength and elastic strain are about 1.3 MPa and about 4%, respectively. However, propagations of shear bands extend along peripheries of the TiB2 particles during compression, which results in fracturing of the matrix prior to yield point and in a decrease in absorbing failure energy within the matrix.